[PROPOSAL] Contribute Stateful Functions to Apache Flink

[Stephan Ewen]

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

[Piotr Nowojski-3]

Hi Stephan,

+1 for adding this to Apache Flink! 

Regarding the question if this should be committed to the main repository or as a separate one, I think it should be the main one. Previously we were discussing the idea of splitting Apache Flink into multiple repositories and I think the consensus was that it would cause more problems compared to the benefits.

Piotrek  

On 11 Oct 2019, at 11:38, Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

[Trevor Grant]

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

[Till Rohrmann]

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

[Jark Wu-3]

Hi Stephan,

big +1 for adding statefun to Apache Flink. 

I think we can add it in the main repository as a library just like State Process API. 

Having it in the main repository can closely co-develop with Apache Flink which be beneficial for both side.

Regards,

Jark

On Fri, 11 Oct 2019 at 19:12, Till Rohrmann <[hidden email]> wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

[Dawid Wysakowicz-2]

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

[Jingsong Li]

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

[jincheng sun]

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[Yu Li]

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[Biao Liu]

Hi Stehpan,

+1 for having Stateful Functions in Flink.

Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion. 

It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.

On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

Best Regards,

Yu

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[Hequn Cheng]

Hi Stephan,

Big +1 for adding this to Apache Flink! 

As for the problem of whether this should be added to the Flink main repository, from my side, I prefer to put it in the main repository. Not only Stateful Functions shares very close relations with the current Flink, but also other libs or modules in Flink can make use of it the other way round in the future. At that time the Flink API stack would also be changed a bit and this would be cool.

Best, Hequn

On Sat, Oct 12, 2019 at 9:16 PM Biao Liu <[hidden email]> wrote:

Hi Stehpan,

+1 for having Stateful Functions in Flink.

Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion. 

It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.

Thanks,

Biao /'bɪ.aʊ/

On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

Best Regards,

Yu

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[Dian Fu]

Hi Stephan,

Big +1 for adding stateful functions to Apache Flink! The use cases unlocked with this feature are very interesting and promising.

Regarding to whether to place it into Flink core repository, personally I perfer to put it in the main repository. This feature introduces a new set of APIs and it will support a new set of applications. It enriches the API stack of Apache Flink. This is somewhat simlar to the Table API & SQL, State Processor API, CEP library, etc. If the applications supported by this feature are important enough for Flink, it's more appropriate to put it directly into the main repository.

Regards,

Dian

在 2019年10月13日，上午10:47，Hequn Cheng <[hidden email]> 写道：

Hi Stephan,

Big +1 for adding this to Apache Flink! 

As for the problem of whether this should be added to the Flink main repository, from my side, I prefer to put it in the main repository. Not only Stateful Functions shares very close relations with the current Flink, but also other libs or modules in Flink can make use of it the other way round in the future. At that time the Flink API stack would also be changed a bit and this would be cool.

Best, Hequn

On Sat, Oct 12, 2019 at 9:16 PM Biao Liu <[hidden email]> wrote:

Hi Stehpan,

+1 for having Stateful Functions in Flink.

Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion. 

It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.

Thanks,

Biao /'bɪ.aʊ/

On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

Best Regards,

Yu

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[Kostas Kloudas-2]

Hi all,

Big +1 for contributing Stateful Functions to Flink and as for the
main question at hand, I would vote for putting it in the main
repository.

I understand that this can couple the release cadence of Flink and
Stateful Functions although I think the pros of having a "you break
it,
you fix it" policy outperform the cons of tying the release cadences.

Looking forward to the integration and the new usecases it may bring!

Cheers,
Kostas

On Mon, Oct 14, 2019 at 9:35 AM Dian Fu <[hidden email]> wrote:

>
> Hi Stephan,
>
> Big +1 for adding stateful functions to Apache Flink! The use cases unlocked with this feature are very interesting and promising.
>
> Regarding to whether to place it into Flink core repository, personally I perfer to put it in the main repository. This feature introduces a new set of APIs and it will support a new set of applications. It enriches the API stack of Apache Flink. This is somewhat simlar to the Table API & SQL, State Processor API, CEP library, etc. If the applications supported by this feature are important enough for Flink, it's more appropriate to put it directly into the main repository.
>
> Regards,
> Dian
>
> > 在 2019年10月13日，上午10:47，Hequn Cheng <[hidden email]> 写道：
> >
> > Hi Stephan,
> >
> > Big +1 for adding this to Apache Flink!
> >
> > As for the problem of whether this should be added to the Flink main repository, from my side, I prefer to put it in the main repository. Not only Stateful Functions shares very close relations with the current Flink, but also other libs or modules in Flink can make use of it the other way round in the future. At that time the Flink API stack would also be changed a bit and this would be cool.
> >
> > Best, Hequn
> >
> > On Sat, Oct 12, 2019 at 9:16 PM Biao Liu <[hidden email] <mailto:[hidden email]>> wrote:
> > Hi Stehpan,
> >
> > +1 for having Stateful Functions in Flink.
> >
> > Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion.
> > It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.
> >
> > Thanks,
> > Biao /'bɪ.aʊ/
> >
> >
> >
> > On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email] <mailto:[hidden email]>> wrote:
> > Hi Stephan,
> >
> > Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.
> >
> > And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.
> >
> > Best Regards,
> > Yu
> >
> >
> > On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email] <mailto:[hidden email]>> wrote:
> > Hi Stephan,
> >
> > bit +1 for adding this great features to Apache Flink.
> >
> > Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.
> >
> > Best,
> > Jincheng
> >
> >
> > Jingsong Li <[hidden email] <mailto:[hidden email]>> 于2019年10月12日周六 上午11:32写道：
> > Hi Stephan,
> >
> > big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.
> >
> > I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.
> >
> > Best,
> > Jingsong Lee
> >
> > On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email] <mailto:[hidden email]>> wrote:
> > Hi Stephan,
> >
> > I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.
> >
> > Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.
> > Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.
> > Best,
> >
> > Dawid
> > [1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html <http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html>
> > [2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws <https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws>
> > On 11/10/2019 13:12, Till Rohrmann wrote:
> >> Hi Stephan,
> >>
> >> +1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.
> >>
> >> One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.
> >>
> >> Cheers,
> >> Till
> >>
> >> On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email] <mailto:[hidden email]>> wrote:
> >> +1 non-binding on contribution.
> >>
> >> Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02.
> >>
> >>
> >>
> >> On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email] <mailto:[hidden email]>> wrote:
> >> Dear Flink Community!
> >>
> >> Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.
> >>
> >> Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)
> >> that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions
> >> that can send each other messages.
> >> As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.
> >> It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.
> >>
> >> You can find out more about it here
> >>   - Website: https://statefun.io/ <https://statefun.io/>
> >>   - Code: https://github.com/ververica/stateful-functions <https://github.com/ververica/stateful-functions>
> >>   - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12 <https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12>
> >>
> >>
> >> Now for the main issue: **We would like to contribute this project to Apache Flink**
> >>
> >> I believe that this is a great fit for both sides.
> >> For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.
> >> Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.
> >> It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.
> >>
> >> There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository
> >> for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.
> >>
> >> Really looking forward to hear what you think!
> >>
> >> Best Regards,
> >> Stephan
> >>
> >
> >
> > --
> > Best, Jingsong Lee
>

[Becket Qin]

+1 to adding Stateful Function to Flink. It is a very useful addition to the Flink ecosystem.

Given this is essentially a new top-level / first-citizen API of Flink, it seems better to have it the Flink core repo. This will also avoid letting this important new API to be blocked on potential problems of maintaining multiple different repositories.

Thanks,

Jiangjie (Becket) Qin

On Sun, Oct 13, 2019 at 4:48 AM Hequn Cheng <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding this to Apache Flink! 

As for the problem of whether this should be added to the Flink main repository, from my side, I prefer to put it in the main repository. Not only Stateful Functions shares very close relations with the current Flink, but also other libs or modules in Flink can make use of it the other way round in the future. At that time the Flink API stack would also be changed a bit and this would be cool.

Best, Hequn

On Sat, Oct 12, 2019 at 9:16 PM Biao Liu <[hidden email]> wrote:

Hi Stehpan,

+1 for having Stateful Functions in Flink.

Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion. 

It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.

Thanks,

Biao /'bɪ.aʊ/

On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

Best Regards,

Yu

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[tison]

+1 to add Stateful Function to FLINK core repository.

Becket Qin <[hidden email]> 于2019年10月14日周一 下午4:16写道：

+1 to adding Stateful Function to Flink. It is a very useful addition to the Flink ecosystem.

Given this is essentially a new top-level / first-citizen API of Flink, it seems better to have it the Flink core repo. This will also avoid letting this important new API to be blocked on potential problems of maintaining multiple different repositories.

Thanks,

Jiangjie (Becket) Qin

On Sun, Oct 13, 2019 at 4:48 AM Hequn Cheng <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding this to Apache Flink! 

As for the problem of whether this should be added to the Flink main repository, from my side, I prefer to put it in the main repository. Not only Stateful Functions shares very close relations with the current Flink, but also other libs or modules in Flink can make use of it the other way round in the future. At that time the Flink API stack would also be changed a bit and this would be cool.

Best, Hequn

On Sat, Oct 12, 2019 at 9:16 PM Biao Liu <[hidden email]> wrote:

Hi Stehpan,

+1 for having Stateful Functions in Flink.

Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion. 

It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.

Thanks,

Biao /'bɪ.aʊ/

On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

Best Regards,

Yu

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee

[Stephan Ewen]

Thank you all for the encouraging feedback! So far the reaction to add this to Flink was exclusively positive, which is really great to see!

To make this happen, here would be the next steps:

(1) As per the bylaws, a contribution like that would need a PMC vote, because it is a commitment to take this and shepherd

it in the future. I will kick that off next.

(2) The biggest open question in the current discussion would be whether to go with a separate repository, or put it into Flink core.

Related to the repository discussion is also how to link and present this on the Flink website.  

I will spin off a separate discussion for that, to keep the threads focused.

Best,

Stephan

On Mon, Oct 14, 2019 at 10:16 AM Becket Qin <[hidden email]> wrote:

+1 to adding Stateful Function to Flink. It is a very useful addition to the Flink ecosystem.

Given this is essentially a new top-level / first-citizen API of Flink, it seems better to have it the Flink core repo. This will also avoid letting this important new API to be blocked on potential problems of maintaining multiple different repositories.

Thanks,

Jiangjie (Becket) Qin

On Sun, Oct 13, 2019 at 4:48 AM Hequn Cheng <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding this to Apache Flink! 

As for the problem of whether this should be added to the Flink main repository, from my side, I prefer to put it in the main repository. Not only Stateful Functions shares very close relations with the current Flink, but also other libs or modules in Flink can make use of it the other way round in the future. At that time the Flink API stack would also be changed a bit and this would be cool.

Best, Hequn

On Sat, Oct 12, 2019 at 9:16 PM Biao Liu <[hidden email]> wrote:

Hi Stehpan,

+1 for having Stateful Functions in Flink.

Before discussing which repository it should belong, I was wondering if we have reached an agreement of "splitting flink repository" as Piotr mentioned or not. It seems that it's just no more further discussion. 

It's OK for me to add it to core repository. After all almost everything is in core repository now. But if we decide to split the core repository someday, I tend to create a separate repository for Stateful Functions. It might be good time to take the first step of splitting.

Thanks,

Biao /'bɪ.aʊ/

On Sat, 12 Oct 2019 at 19:31, Yu Li <[hidden email]> wrote:

Hi Stephan,

Big +1 for adding stateful functions to Flink. I believe a lot of user would be interested to try this out and I could imagine how this could contribute to reduce the TCO for business requiring both streaming processing and stateful functions.

And my 2 cents is to put it into flink core repository since I could see a tight connection between this library and flink state.

Best Regards,

Yu

On Sat, 12 Oct 2019 at 17:31, jincheng sun <[hidden email]> wrote:

Hi Stephan,

bit +1 for adding this great features to Apache Flink.

Regarding where we should place it, put it into Flink core repository or create a separate repository? I prefer put it into main repository and looking forward the more detail discussion for this decision.

Best,

Jincheng

Jingsong Li <[hidden email]> 于2019年10月12日周六 上午11:32写道：

Hi Stephan,

big +1 for this contribution. It provides another user interface that is easy to use and popular at this time. these functions, It's hard for users to write in SQL/TableApi, while using DataStream is too complex. (We've done some stateFun kind jobs using DataStream before). With statefun, it is very easy.

I think it's also a good opportunity to exercise Flink's core capabilities. I looked at stateful-functions-flink briefly, it is very interesting. I think there are many other things Flink can improve. So I think it's a better thing to put it into Flink, and the improvement for it will be more natural in the future.

Best,

Jingsong Lee

On Fri, Oct 11, 2019 at 7:33 PM Dawid Wysakowicz <[hidden email]> wrote:

Hi Stephan,

I think this is a nice library, but what I like more about it is that it suggests exploring different use-cases. I think it definitely makes sense for the Flink community to explore more lightweight applications that reuses resources. Therefore I definitely think it is a good idea for Flink community to accept this contribution and help maintaining it.

Personally I'd prefer to have it in a separate repository. There were a few discussions before where different people were suggesting to extract connectors and other libraries to separate repositories. Moreover I think it could serve as an example for the Flink ecosystem website[1]. This could be the first project in there and give a good impression that the community sees potential in the ecosystem website.

Lastly, I'm wondering if this should go through PMC vote according to our bylaws[2]. In the end the suggestion is to adopt an existing code base as is. It also proposes a new programs concept that could result in a shift of priorities for the community in a long run.

Best,

Dawid

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-Create-a-Flink-ecosystem-website-td27519.html

[2] https://cwiki.apache.org/confluence/display/FLINK/Flink+Bylaws

On 11/10/2019 13:12, Till Rohrmann wrote:

Hi Stephan,

+1 for adding stateful functions to Flink. I believe the new set of applications this feature will unlock will be super interesting for new and existing Flink users alike.

One reason for not including it in the main repository would to not being bound to Flink's release cadence. This would allow to release faster and more often. However, I believe that having it eventually in Flink's main repository would be beneficial in the long run.

Cheers,

Till

On Fri, Oct 11, 2019 at 12:56 PM Trevor Grant <[hidden email]> wrote:

+1 non-binding on contribution. 

Separate repo, or feature branch to start maybe? I just feel like in the beginning this thing is going to have lots of breaking changes that maybe aren't going to fit well with tests / other "v1+" release code. Just my .02. 

On Fri, Oct 11, 2019 at 4:38 AM Stephan Ewen <[hidden email]> wrote:

Dear Flink Community!

Some of you probably heard it already: On Tuesday, at Flink Forward Berlin, we announced **Stateful Functions**.

Stateful Functions is a library on Flink to implement general purpose applications. It is built around stateful functions (who would have thunk)

that can communicate arbitrarily through messages, have consistent state, and a small resource footprint. They are a bit like keyed ProcessFunctions

that can send each other messages.

As simple as this sounds, this means you can now communicate in non-DAG patterns, so it allows users to build programs they cannot build with Flink.

It also has other neat properties, like multiplexing of functions, modular composition, tooling both container-based deployments and as-a-Flink-job deployments.

You can find out more about it here

  - Website: https://statefun.io/

  - Code: https://github.com/ververica/stateful-functions

  - Talk with motivation: https://speakerdeck.com/stephanewen/stateful-functions-building-general-purpose-applications-and-services-on-apache-flink?slide=12

Now for the main issue: **We would like to contribute this project to Apache Flink**

I believe that this is a great fit for both sides.

For the Flink community, it would be a way to extend the capabilities and use cases of Flink into a completely different type of applications and thus grow the community into this new field.

Many discussions recently about evolving the Flink runtime (both on the mailing list and at conferences) show the interest in Flink users in the space that Stateful Functions covers.

It seems natural that Stateful Functions should closely co-develop with Apache Flink, ideally as part of the project.

There are many details to be discusses, for example whether this should be added to the Flink core repository, or whether we and to create a separate repository

for this. But I think we should start discussing this after we have consensus on whether the community wants this contribution.

Really looking forward to hear what you think!

Best Regards,

Stephan

--

Best, Jingsong Lee